This invention relates to integrated circuits and, more particularly, to constant false alarm rate (CFAR) detection circuitry for adaptive target detection in radar systems.
A radar system transmits radio waves which may be reflected or scattered by target objects that are in the path of the radio waves. The radar system may also receive radio waves, which may include components from the target objects as a result of the reflection. However, the radio waves received by the radar system often include additional components caused by noise (e.g., white noise and noise from the equipment), interference with other radio waves, and clutter, which includes echoes from the surrounding landscape (e.g., hills, waves on the sea), wildlife (e.g., birds), atmospheric and meteorological phenomena (e.g., rain or turbulences), and human-made radar countermeasures.
A typical radar system may analyze the received radio waves with the goal of distinguishing between the target objects and the background of clutter, noise and interference. Once a target object has been identified, the radar system may detect the relative range, direction, and speed of the identified target object.
Many modern radar systems use an adaptive algorithm known as constant false alarm rate (CFAR) detection to decide whether a radio signal stems from a target object. Constant false alarm rate detection raises and lowers thresholds above which a target object is detected to maintain a constant probability of false alarm.
A CFAR detection scheme often computes the power level of a cell under test. The CFAR detection scheme also computes the average power level of the cells around the cell under test with the exclusion of immediate neighboring cells in case that a target object's radar response stretches over more than one cell. The CFAR detection may decide that a target object is present in the cell under test if the power level computed for the cell under test is greater than the average power level. Such an approach is also known as cell-averaging constant false alarm rate (CA-CFAR).